Isocyanate functional polymers

ABSTRACT

Isocyanate functional polymers useful as crosslinking agents or as moisture curing polymers, which comprise the addition polymerization reaction product of: 
     (a) 1 to 100% by weight of at least one isocyanate functional ethylenically unsaturated monomer which comprises the reaction product obtained by the gradual addition of an ethylenically unsaturated monomer having a single active hydrogen to a diisocyanate selected from the group consisting of isophorone diisocyanate and 2,4 toluene diisocyanate wherein the final molar ratio of active hydrogen containing monomer to diisocyanate is essentially 1 to 1; and 
     (b) 0 to 99% by weight of at least one ethylenically unsaturated monomer which is free of active hydrogen functionality and which is copolymerizable with the ethylenically unsaturated isocyanate functional monomer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of prior U.S. applicationSer. No. 292,614 filed Dec. 30, 1988 (now U.S. Pat. No. 4,983,676).Application Ser. No. 292,614 was a divisional application of prior U.S.application Ser. No. 814,336 filed Dec. 27, 1985 (now U.S. Pat. No.4,861,853). Application Ser. No. 814,336 was a continuation-in-part ofprior U.S. application Ser. No. 609,943 filed May 14, 1984, nowabandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to novel isocyanate functional polymers which areuseful as crosslinking agents for polymers containing active hydrogenfunctionality, and are also useful as moisture curing polymers.

2. Description of the Prior Art

Isocyanate functional polymers are known in the prior art to be usefulas crosslinking agents in combination with active hydrogen containingmaterials, or by themselves as moisture curing polymers. Thecommercially available isocyanate crosslinkers, however, frequentlycontain free monomeric isocyanate molecules which can cause handlingproblems due to their volatility. This is especially true forpolyisocyanates which are prepared as the biuret of monomericdiisocyanates since that reaction often does not proceed to 100%completion and the reaction may be reversible even under routineconditions of storage and handling.

Other prior art methods of preparing isocyanate functional polymers haveincluded the polymerization of blocked isocyanate containing unsaturatedmonomers such as taught in U.S. Pat. Nos. 3,914,335 and 4,008,247,however, these polymers do not involve free isocyanate.

Although some prior art references, such as West German Patent DE26 18980 C3, teach the preparation of an isocyanate functional unsaturatedmonomer by reacting a diisocyanate and an unsaturated monomer having anactive hydrogen atom, this prior art fails to teach the polymerizationof such monomers to produce isocyanate functional polymers.

SUMMARY OF THE INVENTION

This invention relates to isocyanate functional polymers useful ascrosslinking agents, or as moisture curing polymers wherein the polymercomprises the free radical addition polymerization reaction product of aselected isocyanate functional ethylenically unsaturated monomer andoptionally at least one other ethylenically unsaturated monomer which issubstantially free of active hydrogen functionality. These polymers havespecial utility as moisture curing polymers, crosslinkers for activehydrogen containing polymers and as clear coatings in clearcoat/basecoatmulti-layered coatings.

It is therefore an object of this invention to provide improved moisturecuring polymers. It is another object of this invention to provideungelled polymers having free isocyanate functionality which can beutilized as crosslinking agents for materials containing active hydrogenfunctionality. Another object of this invention is to provide isocyanatefunctional polymers which can be utilized as crosslinkers and/or asmoisture curing polymers reactive at room temperature or at elevatedtemperatures. It is a further object of this invention to provideacrylic polymers which include as at least one of the monomers thereaction product of essentially one mole of a diisocyanate havingdifferent rates of reactivity for each of the isocyanate groups, withessentially one mole of an ethylenically unsaturated monomer havingactive hydrogen functionality. Another object of this invention is toprovide improved pigmented coatings or clearcoats which may comprise theisocyanate functional polymer by itself or as a crosslinker incombination with an active hydrogen containing polymer. These and otherobjects of this invention will be apparent from the followingdescription.

DETAILED DESCRIPTION OF THE INVENTION

The isocyanate functional polymers of this invention comprise thesaturated, ungelled addition polymerization reaction product of:

(a) 1 to 100% by weight of at least one isocyanate functionalethylenically unsaturated monomer which comprises the reaction productobtained by the gradual addition of an ethylenically unsaturated monomerhaving a single active hydrogen to a diisocyanate selected from thegroup consisting of isophorone diisocyanate and 2,4 toluene diisocyanatewherein the final molar ratio of active hydrogen containing monomer todiisocyanate is essentially 1 to 1; and

(b) 0 to 99% by weight of at least one ethylenically unsaturated monomerwhich is free of active hydrogen functionality and which iscopolymerizable with the ethylenically unsaturated isocyanate functionalmonomer.

By saturated and ungelled is meant that the isocyanate functionalpolymers are substantially free of unsaturation and yet are stillsoluble in appropriate solvents.

As mentioned, the isocyanate functional ethylenically unsaturatedmonomer can be conveniently prepared by the gradual addition of anethylenically unsaturated monomer having a single active hydrogen intothe diisocyanate to provide a final molar ratio of essentially 1 to 1.Gradual addition means that less than all of the active hydrogencontaining ethylenically unsaturated monomer required to provide a oneto one molar ratio is initially admixed with the diisocyanate, and thatthe addition will continue over a period of time at a rate designed toallow sufficient mixing of the reactants so that the reaction of theactive hydrogen will preferentially take place with the faster reactingisocyanate group of the diisocyanate. The rate of reaction will bedependent upon the reaction temperature, the efficiency of mixing andthe quantities of the reactants. However, as a general guideline, nomore than about one third of the active hydrogen containing monomershould be added to the diisocyanate in any 20 minute period and it isespecially preferred to extend the addition time over about two to abouteight hours. Active hydrogen functionality means those reactive groupsas determined by the Zerewitinoff Method as described by Kohler in J.Am. Chem. Soc., 49, 3181 (1927). Some such suitable compounds having asingle active hydrogen are, for example, ethylenically unsaturatedcompounds which contain one of the following groups, --OH, --COOH, --SH,or secondary amine --NH.

In order to minimize the manufacture of monomers having twoethylenically unsaturated sites per molecule due to reaction of bothisocyanate groups, it is essential in the practice of this inventionthat the diisocyanate have different rates of reactivity, due to stericand/or electronic effects, for each of its isocyanate groups withrespect to the active hydrogen functionality of the unsaturated monomer.Typically this difference in reactivity can be observed in (i) aromaticdiisocyanates where one isocyanate group is ortho to an alkyl groupwhile the other is not, or, (ii) aliphatic diisocyanates where oneisocyanate group is primary and the other is secondary or tertiary.Especially preferred in the practice of this invention due to theirreactivity and commercial availability are isophorone diisocyanate and2,4-toluene diisocyanate.

In addition to relying on this difference in reactivity, the activehydrogen containing groups should be added gradually over a period oftime, e.g. dropwise or in a steady or intermittent stream, to thediisocyanate to provide a final 1:1 molar ratio of active hydrogenmonomer to diisocyanate so that there is always at least one equivalentof the faster reacting isocyanate group available for reaction with theactive hydrogen group as it is added to the diisocyanate. In fact,although the overall stoichiometry requires essentially one mole ofdiisocyanate for each mole of the active hydrogen containing monomer,throughout much of the reaction time, due to the gradual addition, therewill even be an excess of the equivalents of the faster reactingisocyanate for each equivalent of the active hydrogen group.Additionally, since at least some of the differences in reactivitybetween the two isocyanate groups may depend upon a difference inactivation energy, increases in reaction temperature normally favor thereaction of the slower isocyanate group more than the reaction of thefaster isocyanate group, and therefore, the reaction temperature shouldbe minimized. The reaction should be conducted at less than about 250°F. and, preferably, is maintained between about 60° F. and 180° F.

The reaction between the diisocyanate and the active hydrogen containingmonomer is typically carried out in the presence of a solvent which doesnot contain active hydrogen functionality and the reaction can beconveniently monitored by infrared analysis until essentially all of theactive hydrogen functionality is reacted. Typical solvents includetoluene, xylene, butyl acetate, methyl ethyl ketone etc. If desired, acatalyst for the isocyanate reaction such as metal compounds likedibutyl tin dilaurate, dibutyl tin oxide, zinc napthenate, stannousoxide, or tertiary amines can be added to decrease the processing time.The use of tin catalysts is especially preferred. It is also useful toadd a free radical inhibitor, such as butylated hydroxy toluene to thereaction mixture to prevent premature polymerization of the unsaturatedmonomers.

Preferred ethylenically unsaturated monomers having a single activehydrogen group reactive with the isocyanate representatively have thegeneral formula: ##STR1## wherein R₁ is H or CH₃, A can be branched orstraight chain and is either a carbonyloxyalkylene radical containing 2to about 8 carbon atoms or an aralkylene radical containing 7 to about12 carbon atoms, and Z is OH or NHR₃ wherein R₃ is a straight chain orbranched alkyl radical of 1 to about 6 carbons.

Representative examples of the unsaturated monomer when A is anaralkylene or alkyl substituted aralkylene radical include ortho, meta,and para-vinyl benzyl alcohol, ortho-methyl-paravinyl benzyl alcohol andthe like. Representative examples when A is aralkylene or alkylsubstituted aralkylene and Z is secondary amine functionality includeortho, meta and para vinyl N-methylaniline, ortho-methyl-para-vinylN-methyl aniline and the like.

Representative examples where A is a carbonyloxyalkylene radical aremonomers having the structure: ##STR2## where R₁ and Z are defined asabove and R₂ i a straight chain or branched alkyl radical of 1 to about8 carbons. Monomers having this structure are especially preferred inthe practice of this invention due to their commercial availability andthe facility with which they can be subsequently polymerized.

Representative hydroxyl functional monomers include 2-hydroxyethylacrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate,4-hydroxybutyl methacrylate, 5-hydroxypentyl acrylate,5-hydroxy-3-methylpentyl acrylate, 2-hydroxypropyl acrylate, diethyleneglycol methacrylate etc. These monomers can be conveniently prepared bythe reaction of diols with unsaturated acids such as acrylic ormethacrylic acids.

Representative monomers having secondary amine functionality include theesters prepared by the reaction of monofunctional unsaturated acids suchas acrylic or methacrylic acid with alcohols having pendant secondaryamine groups such as the reaction products of acrylic or methacrylicacid with t-butyl aminoethanol, methylaminoethanol,2-N-methylamino-1-propanol, etc.

When the isocyanate functional ethylenically unsaturated monomerreaction product of this invention is prepared by the gradual additionof the preferred carbonyloxyalkylene active hydrogen containingethylenically unsaturated monomers to the diisocyanate either in thepresence of no catalyst or in the presence of metal catalyst,experimental evidence indicates that a major portion (at least 50% byweight and typically at least 70% by weight) of the reaction productwill be the monoisocyanate functional monomer having the structure:##STR3## wherein R₁ and R₂ are defined as above, Z₁ ═--O-- or ##STR4##where R₃ is a straight chain or branched alkyl radical of 1 to about 6carbons, and

Y is ##STR5##

The isocyanate functional ethylenically unsaturated monomer can behomopolymerized or optionally can be copolymerized with at least oneother ethylenically unsaturated monomer which is substantially free ofactive hydrogen functionality to produce isocyanate functional polymers.Representative ethylenically unsaturated monomers which aresubstantially free of active hydrogen functionality include theunsaturated hydrocarbons such as isoprene, butadiene, ethylene, etc.;vinyl compounds such as styrene, vinyl toluene, vinyl acetate, vinylchloride, etc.; esters of unsaturated acids such as butylacrylate, butylmethacrylate, methyl methacrylate, isobutyl methacrylate, ethylhexylacrylate, isobornyl methacrylate, trimethylolpropane triacrylate, etc.;unsaturated tertiary amines such as 2-(N,N-dimethylamino) ethylacrylate,N-vinyl piperidine, etc.

The isocyanate functional polymers can be prepared by conventional freeradical addition polymerization techniques. Methods of producing acrylicpolymers are well known and are not a part of the present invention. Ifdesired, the free radical polymerization can be catalyzed byconventional catalysts known in the art such as azo, peroxy or redoxcatalysts. Typically, the initiators must be soluble in an organicsolvent and should have a half life of at least about one minute at 250°F. Useful peroxide initiators include di-t-butyl peroxide, t-butylperacetate, t-butyl perbenzoate, dicumyl peroxide and the like. Usefulazo initiators include azobisisobutyronitrile,2-t-butylazo-2-cyanobutane, 1-t-butylazo-1-cyanocylcohexane, and thelike. Typically, the isocyanate functional polymers are produced byheating the unsaturated monomers at temperatures ranging from about 180°F. to about 400° F. and especially 200° F. to about 300° F. to effectthe polymerization. It is normally preferred to prepare the polymers bysolution polymerization in organic solvents. Typically, a mixture of themonomers will be added gradually to a heated solution of the solvent.The solvents should be free of active hydrogen functionality to avoidany reaction of the remaining free isocyanate groups. Useful solventsinclude aromatic hydrocarbons such as toluene, xylene, ethylbenzene,aromatic naphtha, etc.; aliphatic hydrocarbons such as mineral spirits,hexane, aliphatic naphtha, etc., esters such as butyl acetate, ethyleneglycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate,etc.; and ketones such as ethyl amyl ketone, etc. The aromatichydrocarbons and ester solvents are especially preferred. Typically theprogress of the polymerization can be monitored by measuring the NVM(percent weight solids) of the reaction mixture. The number averagemolecular weight of the polymers is typically less than 100,000 andpreferably less than 50,000.

The isocyanate functional polymers prepared by this additionpolymerization reaction can be used as moisture-curing polymers, or ascrosslinkers in combination with active-hydrogen containing polymers.

When used as moisture-curing polymers, the isocyanate functionalpolymers of this invention can contain pigments, catalysts,flexibilizers, flow agents and other additives. It is frequently usefulto add a water scavenger, such as phenyl isocyanate, to the moisturecuring polymers to scavenge any water to provide improved packagestability. The moisture cures can typically be conveniently carried outat temperatures of about 20° C. or greater. Ambient air typically hassufficient moisture to maintain the reaction.

When the isocyanate functional polymers of this invention are used ascrosslinkers they can be used in combination with any active hydrogengroup-containing polymer such as epoxies, alkyds, acrylics, polyesters,polyurethanes, or the like. Typically the active hydrogengroup-containing polymers will have hydroxy or amine functionality asthe active hydrogen group. Normally the isocyanate functional polymerand the active hydrogen-containing polymer are maintained as twoseparate components and then blended shortly before application. Thecoating is then applied to a substrate, such as metal, plastic, wood,glass, paper, synthetic fibers, etc.; by brushing, dipping, rollcoating, flow coating, spraying or other method conventionally employedin the coating industry. The isocyanate functional polymer and theactive hydrogen containing polymer normally will be blended in a ratioto provide at least about 0.5 equivalents of isocyanate for eachequivalent of active hydrogen, and typically the ratio will be betweenabout 0.5 to 3.0 equivalents of isocyanate for each equivalent of activehydrogen. Preferably, about 0.8 to about 1.2 equivalents of isocyanatewill be present for each equivalent of active hydrogen. When used as atwo component system, typically one component will comprise theisocyanate functional polymer as a solvent solution and the othercomponent will comprise the active hydrogen containing polymer whichoptionally may include pigments, flexibilizers, solvents, ultravioletlight stabilizers, or other additives. The two components are usuallymixed together immediately prior to use to prevent prematurecrosslinking. The two component coatings can conveniently be cured attemperatures of about 20° to 150° C.

The isocyanate functional polymers of this invention, either as moisturecuring polymers or as crosslinkers in a two component system have shownspecial utility when utilized in clearcoat/basecoat compositions.

Clearcoat/basecoat systems are well known, especially in the automobileindustry where it is especially useful to apply a pigmented basecoat,which may contain metalic pigments, to a substrate and allow it to forma polymer film followed by the application of a clearcoat which will notmix with or have any appreciable solvent attack upon the previouslyapplied basecoat. The basecoat composition may be any of the polymersknown to be useful in coating compositions.

One useful polymer basecoat includes the acrylic addition polymers,particularly polymers or copolymers of one or more alkyl esters ofacrylic acid or methacrylic acid, optionally together with one or moreother ethylenically unsaturated monomers. These polymers may be ofeither the thermoplastic type or the thermosetting, crosslinking typewhich contain hydroxyl or amine or other reactive functionality whichcan be crosslinked. Suitable acrylic esters for either type of polymerinclude methyl methacrylate, ethyl methacrylate, propyl methacrylate,butyl methacrylate, ethyl acrylate, butyl acrylate, vinyl acetate,acrylonitrile, acrylamide, etc. Where the polymers are required to be ofthe crosslinking type, suitable functional monomers which can be used inaddition to those already mentioned include acrylic or methacrylic acid,hydroxy ethyl acrylate, 2-hydroxy propyl methacrylate, glycidylacrylate, tertiary-butyl amino ethyl methacrylate, etc. The basecoatcomposition may, in such a case, also contain a crosslinking agent suchas a polyisocyanate (including the novel polyisocyanate polymers of thisinvention), a polyepoxide, or a nitrogen resin such as a condensate offormaldehyde with a nitrogeneous compound such as urea, melamine orbenzoguanamine or a lower alkyl ether of such a condensate. Otherpolymers useful in the basecoat composition include vinyl copolymerssuch as copolymers of vinyl esters of inorganic or organic acids, suchas vinyl chloride, vinyl acetate, vinyl propionate, etc., whichcopolymers may be optionally be partially hydrolyzed so as to introducevinyl alcohol units.

Other polymers useful in the manufacture of the basecoat include alkydresins or polyesters which can be prepared in a known manner by thecondensation of polyhydric alcohols and polycarboxylic acids with orwithout the inclusion of natural drying oil fatty acids. The polyestersor alkyds may contain a proportion of free hydroxyl an/or carboxylgroups which are available for reaction, if desired with suitablecrosslinking agents as discussed above.

If desired, the basecoat composition may also contain minor amounts of acellulose ester, to alter the drying or viscosity characteristics of thebasecoat.

Typically, the basecoat will include pigments conventionally used forcoating compositions, such as titanium dioxide, iron oxide, carbonblack, metallic flake pigments such as aluminum flake, copper flake,metalized plastic flake such as metalized Mylar® flake, inorganic flakepigments such as mica flake, organic pigments such as phthalocyanineblue, etc.

Typically, the basecoat is applied to the substrate, which may or maynot previously have been primed, and the basecoat is allowed sufficienttime to form a polymer film which will not be lifted during theapplication of the clearcoat. The clearcoat is then applied to thesurface of the basecoat, and the system can be allowed to dry or, ifdesired, can be force dried by baking the coated substrate attemperatures typically ranging up to about 250° F.

Within the teaching of this invention, the clearcoat may comprise eitherthe isocyanate functional polymer alone, or in combination with anactive hydrogen functional polymer in a two-component system which ismixed together prior to application. Typically, the clearcoat maycontain ultraviolet light absorbers such as hindered phenols or hinderedamines at a level ranging up to about 6% by weight of the vehicle solidsas is well known in the art. When the isocyanate functional polymer isused in a clearcoat composition, or in any composition requiringresistance to ultraviolet light, it is preferred to use the aliphaticdiisocyanate based polymers rather than the aromatic diisocyanateversions since the polymers based upon the aliphatic diisocyanates havebetter resistance to ultraviolet light.

The following examples have been selected to illustrate specificembodiments and practices of advantage to a more complete understandingof the invention. Unless otherwise stated the term "parts" means partsby weight.

EXAMPLE I

An isocyanate functional unsaturated monomer is prepared by charging areaction vessel equipped with stirrer, nitrogen sparge, and droppingfunnel with 2,670 parts of a 50% solution of isophorone diisocyanate(IPDI) in 2-methoxypropyl acetate, 10.56 parts butylated hydroxytoluene, 10.56 parts dibutyltin dilaurate. The mixture was heated to145° F. and continuously purged with nitrogen. 1,564 parts of a 50%solution of hydroxyethyl methacrylate (HEMA) in 2-methoxypropyl acetatewas added dropwise to the reaction mixture over a four and one-half hourperiod. The reaction was monitored by IR until essentially all of thehydroxyl absorption had disappeared and there was no further change inthe urethane absorption. NMR analysis indicated that a major portion(approximately 70% by weight) of the reaction product was an isocyanatefunctional unsaturated monomer having a free primary isocyanate group.The remaining 30% of the reaction product was primarily the diadductcontaining no free isocyanate and two unsaturated functional groups.This is especially surprising in light of prior art teaching whichimplied that primary aliphatic isocyanate groups would react faster thansecondary aliphatic isocyanate groups.

EXAMPLE II

An isocyanate functional unsaturated monomer was prepared by charging areaction vessel equipped as in Example I with 444 parts of a 50% byweight solution of isophorone diisocyanate in 2-ethoxyethyl acetate. 232parts of a 50% solution of 1-hydroxy ethyl acrylate (HEA) in2-ethoxyethyl acetate was added dropwise to the isophorone diisocyanatesolution over about a three our period. The reaction mixture was allowedto stand at room temperature for about 20 hours and then heated to about220° F. and maintained at that temperature for approximately 10 hours.Infrared analysis indicated essentially all of the hydroxylfunctionality had been reacted.

EXAMPLE III

An isocyanate functional unsaturated monomer was prepared by charging areaction vessel equipped as in Example I with 999 parts isophoronediisocyanate, 999 parts xylene, 8 parts dibutyl tin dilaurate, and 8parts butylated hydroxy toluene. The solvent solution was heated toabout 140° F. and a solution of 585 parts hydroxy propyl acrylate (HPA)in 585 parts xylene was added dropwise to the isophorone diisocyanatesolution over about 31/2 hour period. The reaction mixture was held atabout 140° F. for an additional 90 minutes and the reaction mixture wasallowed to cool. Infrared analysis indicated that essentially all of thehydroxyl functionality had been reacted.

EXAMPLE IV

An isocyanate functional unsaturated monomer was prepared by charging areaction vessel with 200 parts 2,4-toluene diisocyanate (TDI), 200 partstoluene, and 1.75 parts butylated hydroxy toluene. A solution of 150parts hydroxy ethyl methacrylate in 150 parts toluene was added dropwiseto the 2,4-toluene diisocyanate/toluene solution over a period of about41/2 hours. During this addition time the reaction temperatureexothermed from about 76° F. to about 90° F. The reaction mixture wasallowed to cool and infrared analysis indicated that essentially all ofthe hydroxyl functionality had been reacted.

EXAMPLE V

An isocyanate functional unsaturated monomer was prepared by charging areaction vessel with 425 parts isophorone diisocyanate, 3.9 partsbutylated hydroxy toluene, 779 parts xylene and 3.9 parts dibutyl tindilaurate. The reaction mixture was heated to about 140° F. and 354parts tertiary butyl amino ethyl methacrylate (TBAEMA) was addeddropwise to the isocyanate solution over a period of about 3 hours. Thereaction temperature was maintained at about 140° F. for an additionaltwo hours after which the reaction mixture was allowed to cool. Infraredanalysis indicated that essentially all of the secondary aminefunctionality had been reacted.

EXAMPLE VI

An acrylic resin having free isocyanate functionality was prepared byadding 426 parts xylene into a reaction vessel containing a thermometer,nitrogen inlet, and stirring shaft. The mixture was heated to 210° F.and maintained at that temperature under nitrogen purge for five hourswhile a mixture of:

    ______________________________________                                        Raw Materials        Parts By Weight                                          ______________________________________                                        HEMA/IPDI Adduct of Example I                                                                      1620                                                     Isobornyl methacrylate                                                                             102                                                      Isobutyl methacrylate                                                                              102                                                      Vazo 64.sup.1         41                                                      ______________________________________                                         .sup.1 1,1azobis-(isobutyronitrile)                                      

was added dropwise to the heated solvent solution.

The reaction was maintained at 210° F. for approximately one hour and 45minutes after the addition was completed to produce an acrylic polymerhaving an NVM of 45.2% and a percent NCO on solution of 4.30.

EXAMPLE VII

In a manner similar to that of Example VI, an acrylic vehicle wasprepared by adding 337 parts butyl acetate solvent to a reaction vesseland maintaining the temperature at approximately 210° F. for about fivehours while a mixture of:

    ______________________________________                                        Raw Materials        Parts by Weight                                          ______________________________________                                        HEMA/IPDI adduct of Example I                                                                      1575                                                     Styrene              169                                                      Butyl Methacrylate   169                                                      Vazo 67.sup.1         45                                                      ______________________________________                                         .sup.1 2,2azobis-(2-methylbutyronitrile)                                 

was added to the heated solvent mixture.

The reaction was maintained at 210° F. for one hour after the additionwas completed yielding an isocyanate functional acrylic resin with anNVM of about 51%.

EXAMPLE VIII

In a manner similar to that of Example VI, an acrylic homopolymer wasmanufactured by heating 300 parts butyl acetate solvent to about 210° F.followed by the addition of the following mixture of raw materials overabout a five hour period:

    ______________________________________                                        Raw Materials        Parts by Weight                                          ______________________________________                                        HEMA/IPDI adduct of Example I                                                                      2250                                                     Vazo 64               45                                                      ______________________________________                                    

The reaction mixture was maintained at about 210° F. for an additionalhour after all of the monomer was added. The isocyanate functionalhomopolymer prepared in this manner had excellent clarity and an NVM ofabout 46%.

EXAMPLE IX

In a manner similar to that of Example VI an acrylic vehicle wasmanufactured by adding to a heated solution of 683 parts butyl acetate,the following materials:

    ______________________________________                                        Raw Materials        Parts by Weight                                          ______________________________________                                        HEMA/IPDI adduct of Example I                                                                      735                                                      Methyl methacrylate  262                                                      Styrene              158                                                      Butyl Methacrylate   263                                                      Vazo 64               37                                                      ______________________________________                                    

The mixture was added dropwise over a period of about six hours and thereaction mixture was maintained at about 215°-220° F. for an additionalhour to yield an isocyanate functional acrylic polymer having an NVM ofabout 55%.

EXAMPLE X

An acrylic resin having free isocyanate functionality was prepared byadding 109.8 parts 2-ethoxyethyl acetate into a reaction vesselcontaining a thermometer, nitrogen inlet, and stirring shaft and heatedto 240° F. under a nitrogen purge. Over a three hour period a mixtureof:

    ______________________________________                                        Raw Materials        Parts by Weight                                          ______________________________________                                        HEA/IPDI adduct of Example II                                                                      94.5                                                     Butyl acrylate       18.8                                                     Styrene              18.8                                                     Methyl methacrylate  25.0                                                     Vazo 64               6.3                                                     ______________________________________                                    

was added to the heated solvent solution.

After the addition was completed, the reaction mixture was held atapproximately 240° F. for approximately two hours and then an additional2.0 parts of Vazo 64 in 10 parts 2-ethoxyethyl acetate, was added to themixture. The reaction mixture was maintained at approximately 240° F.for an additional six hours to yield a clear, low viscosity isocyanatefunctional resin having an NVM of about 37%.

EXAMPLES XI

A polymer having free isocyanate functionality was prepared by adding563 parts xylene to a reaction vessel equipped as described in ExampleX. The solvent was heated to 225° F., maintained under a nitrogen purge,and over a period of about 4 hours a mixture of:

    ______________________________________                                        Raw Materials        Parts by Weight                                          ______________________________________                                        HPA/IPDI Adduct of Example III                                                                     1125                                                     Butyl methacrylate   281                                                      Methyl methacrylate  281                                                      Vazo 67               51                                                      ______________________________________                                    

was added to the heated solvent solution.

After the addition was complete the reaction mixture was maintained atabout 225° F. for about two hours to yield a clear, low viscosityisocyanate functional resin having an NVM of about 49.3%.

EXAMPLE XII

An isocyanate functional polymer was prepared by adding 300 parts butylacetate to a reaction vessel equipped as described in Example X. Thesolvent was heated to approximately 210° F. and maintained at thattemperature under a nitrogen purge for approximately five hours while amixture of:

    ______________________________________                                        Raw Materials         Parts by Weight                                         ______________________________________                                        HEMA/TDI adduct of Example IV                                                                       600                                                     Styrene               150                                                     Butyl acrylate        60                                                      Methyl Methacrylate   90                                                      Vazo 64               10                                                      ______________________________________                                    

was added dropwise to the heated solvent solution.

The reaction was maintained at about 210° F. for an additional hourafter the addition was completed to produce an acrylic polymer having anNVM of about 42%.

EXAMPLE XIII

An isocyanate functional polymer was prepared by adding 813 parts xyleneto a reaction vessel equipped as described in Example X. The xylene washeated to about 215° F. and maintained at that temperature under anitrogen purge for approximately four hours while a mixture of:

    ______________________________________                                        Raw Materials          Parts by Weight                                        ______________________________________                                        TBAEMA/IPDI adduct of Example V                                                                      875                                                    Methyl methacrylate    313                                                    Butyl methacrylate     313                                                    Styrene                188                                                    Vazo 67                 56                                                    ______________________________________                                    

was added dropwise to the heated solvent solution. An additional 11parts Vazo 67 in 100 parts xylene was added to the reaction mixture andthe mixture was maintained at about 215° F. for about three hours toyield a low viscosity resin solution having an NVM of about 48.1%.

EXAMPLE XIV

A moisture curing primer was prepared according to the following recipe:

    ______________________________________                                        Raw Materials   Parts by Weight                                               ______________________________________                                        Soya lecithin    3                                                            Xylene          81                                                            Magnesium silicate                                                                            129                                                           Barytes         28                                                            Titanium dioxide                                                                              46                                                            Phenyl isocyanate                                                                              8                                                            ______________________________________                                    

This mixture was ground to about 5H hegman by shaking the mixture withglass beads for about one hour. Then the following materials were added.

    ______________________________________                                        Raw Materials           Parts by Weight                                       ______________________________________                                        Toluene                  50                                                   HEMA/IPDI homopolymer of Example VIII                                                                 210                                                   ______________________________________                                    

The beads were filtered from the mixture and the coating was sprayapplied to a metal panel and allowed to air dry at room temperatureproducing a hard cured primer finish.

EXAMPLE XV

A clearcoat was prepared by mixing:

    ______________________________________                                        Raw Materials       Parts by Weight                                           ______________________________________                                        Isocyanate functional polymer of                                                                  75                                                        Example XIII                                                                  Toluene             66                                                        Xylene              14                                                        Zinc Napthanate (8%)                                                                                1.5                                                     Tinuvin.sup.1 292     0.8                                                     ______________________________________                                         .sup.1 trademark of CibaGeigy for                                             bis(1,2,2,6,6pentamethyl-4-piperdinyl)sebacate light stabilizer          

A clearcoat/basecoat system was prepared by priming a steel panel with adry film thickness of about 1.7 mils of a commercially availableautomotive primer. A commercially available white automotive acryliclacquer basecoat was applied to the primer to provide a dry filmthickness of about 3.0. The basecoat was then topcoated with the clearformulation of this example to provide a dry film thickness of the clearof about 1.4 mils. The basecoat/clearcoat system provided excellent 60and 20° gloss, a tack free time of about 3 hours, and excellent hardnessafter air drying at room temperature for one day.

EXAMPLE XVI

A clearcoat formulation was prepared by mixing:

    ______________________________________                                        Raw Materials       Parts by Weight                                           ______________________________________                                        Isocyanate functional polymer of                                                                  75                                                        Example XI                                                                    Toluene             66                                                        Aromatic Naptha     9                                                         Methyl n-amyl ketone                                                                              4.5                                                       Zinc Napthanate (8%)                                                                              1.5                                                       Tinuvin ® 292   0.4                                                       Tinuvin ® 328   0.4                                                       ______________________________________                                    

A clearcoat/basecoat system was prepared by applying a 2.0 mil dry filmthickness of commercially available automotive primer, followed by 2.8mil dry film thickness of commercially available acrylic lacquerbasecoat, followed by 1.5 mils dry film thickness of the clear coatingof this example. Each of the coats were spray applied. The clearcoat wastack free in approximately 31/2 hours and the clearcoat/basecoat systemshowed excellent 60° and 20° gloss, excellent hardness and, after oneweek air dry showed excellent resistance to solvents such as xylene andmethyl ethyl ketone.

EXAMPLE XVII

A clear coating comprising a mixture of:

    ______________________________________                                        Raw Materials   Parts by Weight                                               ______________________________________                                        Acryloid AU-608.sup.1                                                                          500.0                                                        Toluene         1000.0                                                        Xylene          1000.0                                                        Tinuvin.sup.2 770                                                                               3.0                                                         Tinuvin.sup.3 328                                                                               3.0                                                         ______________________________________                                         .sup.1 Hydroxylfunctional acrylic resin sold by Rohm & Haas Company havin     an NVM of approximately 60% and a hydroxyl equivalent weight (solids          basis) of 600.                                                                .sup.2 Trademark of CibaGeigy for di[4(2,2,6,6 tetramethyl                    piperdinyl)]sebacate light stabilizer.                                        .sup.3 Trademark of CibaGeigy for 2(2 hydroxy3,5-ditertiary                   amylphenol)-2H-benzotriazole.                                            

was prepared as one component and then mixed with 386 parts of theisocyanate functional polymer of Example VIII as the second component togive an NCO/OH ratio of about 1.2:1. This coating was spray applied andair dried to produce a hard, glossy cured film having excellentdurability.

EXAMPLE XVIII

A clear solution was prepared by mixing:

    ______________________________________                                        Raw Materials       Parts by Weight                                           ______________________________________                                        Isocyanate functional polymer of                                                                  63.0                                                      Example IV                                                                    Toluene             22.0                                                      Aromatic naptha     3.0                                                       Xylene              6.0                                                       Flexol 4G0.sup.1    2.0                                                       Zinc octoate        1.0                                                       Tinuvin 292         0.7                                                       ______________________________________                                         .sup.1 Flexibilizer manufactured by Union Carbide.                       

A crosslinked basecoat was prepared by mixing one quart of theabove-described clear solution into one gallon of a commerciallyavailable acrylic modified alkyd (Acrylyd® acrylic manufactured by TheSherwin-Williams Company). This basecoat was spray applied to a metalsubstrate and allowed to air dry. The basecoat was then topcoated byspray application of the clear solution described above. The clearcoatwas then allowed to air dry yielding a cured, solvent resistantclearcoat/basecoat finish having excellent gloss.

EXAMPLE XIX

A clear coating was prepared by mixing:

    ______________________________________                                        Raw Materials           Parts by Weight                                       ______________________________________                                        QR-765M.sup.1           300                                                   Ethyl ortho formate      10                                                   Xylene                  300                                                   Dibutyl tin dilaurate    2                                                    HEMA/IPDI homopolymer of Example VIII                                                                 950                                                   ______________________________________                                         .sup.1 Amine functional acrylic resin manufactured by The Rohm & Haas         Company having an NVM of 50.5%, pH (as supplied) of 10.0, an amine            equivalent weight (solid basis) of 165 and a density of 8.6 pounds per        gallon.                                                                  

to give an NCO/amine equivalent ratio of approximately 1.5:1.0. Theethyl ortho formate is used to scavenge any water remaining in theQR-765M. This clear can be spray applied and allowed to air dry toproduce a hard, solvent resistant film.

While this invention has been described by a specific number ofembodiments, it is obvious that other variations and modifications maybe made without departing from the spirit and scope of the invention asset forth in the appended claims.

The invention claimed is:
 1. In a substrate coated with a multi-layerdecorative and/or protective coating which comprises:(a) a base coatcomprising a pigmented film-forming polymer; and (b) a transparent clearcoat comprising a film-forming polymer applied to the surface of thebase coat composition;the improvement which comprises utilizing as theclear coat a moisture curable isocyanate functional polymer whichcomprises the saturated, ungelled addition polymerization reactionproduct of: (i) 1 to 100% by weight of at least one isocyanatefunctional ethylenically unsaturated monomer which comprises thereaction product obtained by the gradual addition of an ethylenicallyunsaturated monomer having a single active hydrogen to a diisocyanateselected from the group consisting of isophorone diisocyanate and 2,4toluene diisocyanate wherein the final molar ratio of active hydrogencontaining monomer to diisocyanate is essentially 1 to 1; and (ii) 0 to99% by weight of at least one ethylenically unsaturated monomer which isfree of active hydrogen functionality and which is copolymerizable withthe ethylenically unsaturated isocyanate functional monomer.
 2. Thecoated substrate of claim 1 wherein the isocyanate functional polymer isfurther characterized in that the ethylenically unsaturated monomerhaving a single active hydrogen has the structure: ##STR6## wherein R₁is H or CH₃ ; A is straight chain or branched and is either acarbonyloxyalkylene radical containing 2 to about 8 carbon atoms or anaralkylene radical containing 7 to about 12 carbon atoms, and Z is OH orNHR₃ wherein R₃ is a straight chain or branched alkyl radical of 1 toabout 6 carbons.
 3. The coated substrate of claim 1 wherein theisocyanate functional polymer is further characterized in that theethylenically unsaturated monomer having a single active hydrogen hasthe structure: ##STR7## wherein R₁ is H or CH₃ ; R₂ is a straight chainor branched alkyl radical of 1 to about 8 carbons; andZ is OH or NHR₃where R₃ is a straight chain or branched alkyl radical of 1 to about 6carbons.
 4. The coated substrate of claim 1 wherein the isocyanatefunctional polymer is further characterized in that a major portion ofthe reaction product obtained by the reaction of the diisocyanate andthe active hydrogen functional unsaturated monomer is an isocyanatefunctional ethylenically unsaturated monomer having the structure:##STR8## wherein R₁ ═H or CH₃ ; R₂ ═a straight chain or branched alkylradical of 1 to about 6 carbons;Z₁ ═--O-- or ##STR9## where R₃ is astraight chain or branched alkyl radical of 1 to about 6 carbons; and Yis ##STR10##
 5. In a substrate coated with a multi-layer decorativeand/or protective coating which comprises:(a) a base coat comprising apigmented film-forming polymer; and (b) a transparent clear coatcomprising a film-forming polymer applied to the surface of the basecoat composition;the improvement which comprises utilizing as the clearcoat a two component coating which is mixed prior to application, thecoating comprising an active hydrogen functional polymer and anisocyanate functional polymer, wherein the isocyanate functional polymercomprises the saturated, ungelled addition polymerization reactionproduct of: (i) 1 to 100% by weight of at least one isocyanatefunctional ethylenically unsaturated monomer which comprises thereaction product obtained by the gradual addition of an ethylenicallyunsaturated monomer having a single active hydrogen to a diisocyanateselected from the group consisting of isophorone diisocyanate and 2,4toluene diisocyanate wherein the final molar ratio of active hydrogencontaining monomer to diisocyanate is essentially 1 to 1; and (ii) 0 to99% by weight of at least one ethylenically unsaturated monomer which isfree of active hydrogen functionality and which is copolymerizable withthe ethylenically unsaturated isocyanate functional monomer.
 6. Thecoated substrate of claim 5 wherein the isocyanate functional polymer isfurther characterized in that the ethylenically unsaturated monomerhaving a single active hydrogen has the structure: ##STR11## wherein R₁is H or CH₃ ; A₂ is straight chain or branched and is either acarbonyloxyalkylene radical containing 2 to about 8 carbon atoms or anaralkylene radical containing 7 to about 12 carbon atoms, and Z is Oh orNHR₃ wherein R₃ is a straight chain or branched alkyl radical of 1 toabout 6 carbons. PG,33
 7. The coated substrate of claim 5 wherein theisocyanate functional polymer is further characterized in that theethylenically unsaturated monomer having a single active hydrogen hasthe structure: ##STR12## wherein R₁ is H or CH₃ ; R₂ is a straight chainor branched alkyl radical of 1 to about 8 carbons; andZ is OH or NHR₃where R₃ is a straight chain or branched alkyl radical of 1 to about 6carbons.
 8. The coated substrate of claim 5 further characterized inthat a major portion of the reaction product obtained by the reaction ofthe diisocyanate and the active hydrogen functional unsaturated monomeris an isocyanate functional ethylenically unsaturated monomer having thestructure: ##STR13## wherein R₁ ═H or CH₃ ; R₂ ═a straight chain orbranched alkyl radical of 1 to about 6 carbons;Z₁ ═--O-- or ##STR14##where R₃ is a straight chain or branched alkyl radical of 1 to about 6carbons; and Y is ##STR15##